Additive Manufacturing (AM) encompasses a variety of forms to cover an entire range of quick-response direct fabrication, typically in a layered format, of end-use articles. These end use articles generally exhibit high geometric customization, such as hearing aids, dental implants and customized applications. In addition, AM may also exhibit relatively low production volume for applications residing in formula car racing, aerospace and medical industries, for example and without limitation.
AM technologies have proven their capabilities for mass-customized production in different domains. The robustness of these technologies has not completely been demonstrated in a mass production context. In aerospace applications, mechanical property performance is important. The end-use parts fabricated using AM must meet the requirements of the design engineer. A common type of additive manufacturing process is known as fused Deposition Modeling (FDM).
Fused Deposition Modeling (FDM) is an extrusion-based process that feeds material in solid wire form and then melts it into a shape and forms a solid. FDM is a nonlaser filament extrusion process that may utilize engineering thermoplastics, which may be heated from filament form and extruded in very fine layers to build each model from the bottom up. The models may be made from acrylonitrile butadiene styrene (ABS), polycarbonate, polyphenylsulfone (PPSF), and various versions of these materials. Furthermore, in many cases, the models may be tough enough to perform functional tests. The material used is fed into an extrusion head in solid wire form and then liquefied in the extrusion head and deposited through a nozzle in liquid form. The extrusion head is able to move in the X-Y plane and is controlled to deposit very thin beads of molten material onto the build platform to form the first layer.
Aerospace and other applications may demand that rigorous testing and certification be carried out preparatory to using materials and processes for the manufacture of components. Moreover, specific material requirements may be associated with the part candidates for aircraft and other structures. In order for additive manufacturing to become fully adopted as a credible manufacturing process, it may be necessary to organize a path that provides a roadmap to production for candidate parts that are inclined to become AM candidate parts.
For FDM and other additive manufacturing processes such as SLS (Selective Laser Sintering), Z axis orientation of parts may be generally weaker than both X and Y directions of the parts. This Z axis limiting effect may be due primarily to the additive nature inherent in most all RM processes. Due to the Z axis limitation, design engineers may limit the technology to the weakest anisotropic plane and place emphasis on Z axis testing. This emphasis on Z axis testing may be relevant for many testing types. Due to budget constraints, industry may focus on one or two types of testing techniques that simulate physical conditions of applications and a large population of samples. This constraint has lead to an overall decision to test for both uniaxial tensile and flexural tests.
The additive manufacturing industry does not currently have a standard for building Z-axis (vertical) tensile bar coupons for processes that require support material. Therefore, a Z-axis test coupon structure and a quick and repeatable method for producing Z-axis (vertical) test coupons in additive manufacturing processes that require support structure are needed.